1. Field of the Invention
The present invention relates to a belt device for use in an image forming apparatus.
2. Description of the Related Art
Tandem color image forming apparatuses, such as copiers and printers, including an intermediate transfer belt (belt device) are well-known in the art. Such image forming apparatuses have been disclosed in, for example, Japanese Patent Application Laid-open No. 2004-341087 and Japanese Patent No. 3473148.
In a typical image forming apparatus, four photosensitive drums (image carriers) are provided side by side facing an intermediate transfer belt (belt member). Single-color toner images for black, yellow, magenta, and cyan are respectively formed on each of the four photosensitive drums. Those single-color toner images are then transferred so as to be overlaid on top of each other on the intermediate transfer belt to form a color toner image on the intermediate transfer belt. The color toner image supported on the intermediate transfer belt is then transferred to and fixed on a recording medium, such as a paper, as a color image.
Configurations where an intermediate transfer belt device can be pulled out to the front with respect to an image forming apparatus body are common. Such a configuration makes maintenance of the intermediate transfer belt device straightforward. Specifically, in Japanese Patent Application Laid-open No. 2004-341087, a transfer module fitted with an intermediate transfer belt is mounted on an intermediate transfer belt device. After then pulling the intermediate transfer belt device (transfer unit) to the front with respect to the image forming apparatus body, the transfer module mounted on the intermediate transfer belt device can be detached from above.
With the image forming apparatus of Japanese Patent Application Laid-open No. 2004-341087, it is necessary for the transfer module mounted on the intermediate transfer belt apparatus to be detached upwards after the intermediate transfer belt device (belt device) is pulled out to the front with respect to the image forming apparatus body while changing the intermediate transfer belt (belt member). However, in this configuration, ease of maintenance (maintenance operativity) of the intermediate transfer belt device, such as changing of the intermediate transfer belt, drops.
In order to resolve this situation, it is therefore preferable to ensure that maintenance of the intermediate transfer belt device is possible in a state where the intermediate transfer belt device is pulled out to the front with respect to the image forming apparatus body. This can, however, cause a frame of the intermediate transfer belt device to deform as a result of the intermediate transfer belt device being pulled out with respect to the image forming apparatus body for a long period of time. Deformation of the frame of the intermediate transfer belt device can lead to misalignment of various components mounted on the frame and can cause degradation of image quality. This problem is particularly difficult to ignore in large image forming apparatus where the weight of the intermediate transfer belt apparatus is substantial. The outer periphery of the intermediate transfer belt of conventional apparatus is substantially covered by a frame. It is therefore not possible to change the intermediate transfer belt with a single action in a state where the intermediate transfer belt device is pulled out to the front with respect to the image forming apparatus body.